td,
th {
    text-align: center;
}

body {
    background: url(../images/水印.png) ;
    font-size: 20px;
}

table {
    margin-left: auto;
    margin-right: auto;
    width: 50%;
}

#first {
    color: #39c5bb;
}

#second {
    color: red;
}

#third {
    color: #66ccff;
}